This invention relates to test fixtures used in testing RF transistors in microwave frequencies (see ref. 1, 2). Active RF components (transistors—DUT) need to be thoroughly tested at the operation frequencies before used in amplifier and other circuit designs. “Load pull” and “Source pull” (see ref. 3) are test methods which use impedance tuners to systematically characterize the DUTs under various load and source impedance conditions. Load pull or source pull are automated measurement techniques used to measure Gain, Power, Efficiency and other characteristics of the DUT, employing, beyond source and load impedance tuners, also other test equipment, such as signal sources, directional couplers, test fixtures to house the DUT and input and output power meters (FIG. 1), see ref. 3. Typical test fixtures (see ref. 2) used are based on micro-strip structure (FIG. 2). Signal power from the signal source is measured by the input power meter and injected into the DUT through the source tuner. The power generated by the DUT is measured by the output power meter after traversing the output tuner. The tuners generate the source and load impedances required for the testing. Prior component calibration (test fixture, tuners, couplers etc.) allows de-embedding measured data from the power meters to the DUT reference plane.
Test fixtures (FIG. 2 or 3) include grounded input (22, 213) and output (28, 215) body sections, a cover ((10) in FIG. 3) and a DUT INSERT (21, 23, 214). The DUT (210) is mounted on the INSERT (214) using screws (26) or other securing mechanism. The fixture has input (20) and output (27) connectors and microstrip lines (29, 212) between the connectors. The microstrip lines comprise a dielectric layer on which a thin copper conductor layer (29, 212) remains after etching using acids and photolithographic process. The DUT (210) package has leads (51, 52, 24, 211) which can be soldered or secured on the microstrip (29, 212), see FIG. 5 and ref. 4.